KEYRING Hanayama Cast Metal Brain Teaser Puzzle (Level 2) Hanayama's Keyring Puzzle is a high quality cast metal brain teaser from inventor Oskar van Deventer Discover how to separate these two interlocking pieces and then try to reassemble them! Hanayama cast metal brain teasers have 6 levels of difficulty and each puzzle is Mensa-rated Level 2 puzzles are considered fairly easy by most puzzlers